Process for separation of nickel from cobalt in ocean floor manganiferous ore deposits



Feb. 16, 1965 J 3,169,856

l L. MERO PROCESS FOR SEPARA'I: ON OF NICKEL FROM COBALT IN OCEAN FLOORMANGANIFEROUS ORE DEPOSITS Filed May 22, 1962.

GRAPH SHOWING COMPARATIVE LEACHING RATES OF MANGANESE AND OF IRONMINERALS LEACHING CURVE FOR Ni-Cu IN Mn PHASE I Mn-Ni LEACHING CUT OFFPOINT PERCENT OF METALS LEACHED LEACHING CURVE FOR Co IN Fe PHASEINVENTOR JOHN L. MERO ATTORNEY$ United States Patent 0,

PROCESS FOR SEPARATION OF NECKEL FROM COBALT IN OCEAN FLOORMANGANKFEROUS ORE DEPOSITS John L. Mero, Berkeley, Caiii. (1091 ViaRobles, Lafayette, Calif.) Filed May 22, 1962, Ser. No. 196,777 4Claims. (ill. 751l9) My invention relates to a process for recoveringnickel, cobalt and other metals from ocean floor m'anganiferous oredeposits, and more particularly relates to a process of separating thenickel from the cobalt found in ocean floor manganiferous deposits.

Although termed manganese deposits or manganiferous ore deposits byvirtue of the fact that manganese, on a weight basis, is most frequentlythe major metallic constit- "uent of these ore deposits, the ocean floormineral deposits contain many other elements of economic interest asshown in the following table:

MAXIMUM, MINIMUM, AND AVERAGE WEIGHT PERCENTAGES OF 27 ELEMENTS INMANGA- NESE DEPOSITS FROM THE PACIFIC AND AT- LANTIC OCEANS Weightpercentages (dry weight basis) Pacific Ocean-Statistics AtlanticOcea.nStatison 54 Samples ties on 4 Samples Element Minimum MinimumMaximum Average Average 1 As determined by X-ray emission spectrography.

2 Average of 5 samples in which Ag was detected.

3 L.O.I.=L0ss on ignition at 1,100 F. for one hour. The L.O.I. fig uresare based on a total weight of air-dried sample basis.

Ocean floor mineral deposits containing substantial amounts ofmanganese, nickel, cobalt, and copper were discovered in 1873 by theBritish Oceanographic Challenger Expedition. Subsequent oceanographicexpeditions have recovered samples of these deposits from many 3,169,855Patented Feb. 16, 1965 Of the many ingredients making up such oredeposits, nickel and cobalt are emphasized because, firom an economicstandpoint, they are the most significant metals in most of these seafloor ores. Other metals, normally present, will be recovered asby-products in the production of nickel and cobalt.

Known methods of separating nickel and cobalt as found in natural ores,generally depend on some method of indiscriminately leaching theseelements and separating the same after they are in solution together.Such nickelcobalt separations, however, are rather diflicult andexpensive to carry out.

The mining of the vast reserves of manganiferous deposits lying over theocean floor, can best be economically justified, were a more economicalprocess avail-able to efiect a separation and ultimate recovery of thenickel and cob-alt elements.

Accordingly, among the objects of my invention are:

(1) To provide a novel and improved process of separating the nickelfrom the cobalt as found in ocean floor manganiferous deposits;

(2) Toprovide a novel and improved process of separating the nickel fromthe cobalt as found in ocean floor manganiferous deposits, which processshall be simple and straight-forward;

' (3) To provide a novel and improved process for separating the nickelfrom the cobalt as found in ocean floor deposits, which process, at thesame time facilitates the recovery of the many other elements involvedin such deposits.

(4) To provide a novel and improved process for separating the nickelfrom the cobalt as found in ocean floor deposits, which processprovide-ssimple but accunate controls for indicating substantiallycomplete separation of such elements from each other.

Additional objects of my invention will be described in conjunction withthe accompanying drawing wherein the figure is a graph depicting theprinciple underlying the present invention.

Following intensive investigation of these ocean floor mineral deposits,I have discovered them to consist of several separate mineral. phases ofmanganese and of iron. These separate mineral crystallites of manganeseand of iron are so fine-grained and so intimately mixed that no knownphysical process can be employed to separate them. The minor metallicconsituents of the ocen floor manganifenou deposits, such as nickel,cobalt, and co er and other elements, are localized in different mineralphases of this material, some elements being contained in the manganesemineral phases and others in the iron mineral phases.

I have found, through my extensive investigations, that the nickel andcopper are contained in the manganese mineral phase of this material,apparently in solid solution in the manganese minerals. Cobalt, on theother hand, I have discovered to exist in the iron mineral phases ofthis material to the exclusion of the manganese phase. This is unlikethe situation existing in connection with conventional ore involvingnickel and cobalt, in which ores, when the nickel and cobalt areintimately mixed, must be indiscriminately leached from the ore, as thefirst step in effecting a separation thereof, but which step,unfortunately places them both in solution together, which in turnraises the problem of separation of the nickel from the cobalt.

The present invention is predicated upon the aforementioned discovery ofmine relating to the phase characteristics of the ocean floor mineraldeposits under consideration herein, and basically involves a processfor differentially leaching these metals from the manganiferous orebeiore they are both in solution together, which process is madepossible by such discovery.

To accomplish such separation of the nickel room the cobalt in themangani-ferous deposits found on the ocean floor, the ore is firstcrushed preferably to about minus forty mesh. The crushed ore materialis then mixed with water to form an aqueous slurry which consists of notmore than about 40 pence'nt of crushed ore by weight. The amount ofcrushed ore in this slurry is not critical but should be sufficient'toallow the mixture to act fluid. Leaching gases, which may be sulphurdioxide, nitrogen dioxide or other gases that reduce manganese and ironoxides of a high oxidation state, are then mixed with the aqueou slurry.This may be accomplished by percolating the gas up through the slurrywhile maintaining the slurry in a constant state of agitation. When theslurry is thus exposed to the gas, the manganese along with the nickel,copper and other mineral elements bound up in the manthe cobalt or ironcontent of the resulting solution begins ganese phase of the ore, willgo into solution in accordance V with the leaching curve of the drawing,designated as Leaching Curve for Ni'-Cu in Mn Phase, while the ironalong with the cobalt bound up in the iron phase,

nickel, copper and such other elements in the manganese phase, will gointo solution before any appreciable amounts I of thecobalt and suchother elements as may be bound up in the i-ronphase; After all theavailable manganese, nickel, copper, etc., are in solution, additionalamounts of gas added to the aqueous slurry, will cause a change in thepH of the slurry toward the'acidic andonly then will much of the cobaltor iron start to dissolve. 1 It is at this point, that the process isstopped and the separation effected, because at this point, the nickeland associated elements are all in solution, while the cobalt and itsassociated elements are still in solid state. This critical point canthus be controlled by continuous monitoring of the pH of the aqueousslurry.

Another indication of the complete dissolution of the i nickel and othermetals associated in the manganese phase,

will be the evolution of leaching gas from the top of the leaching cell.Evolution of such leaching gas or the sudden change in the pH of theslurry, therefore, can be used as controls to prevent the dissolving ofthe cobalt and other elements associated with the iron phase in the orematerial.

This leaching proces may be batch-wise or continuous. At the completionof the leaching operation in a batch process, the leaching gases arestopped and the solution is separated from the tailings. In a continuousprocess, solution would be continuously drawn off, ore, leaching gases,and Water continuously added and the tailings continuously removed. ThepH of the solution and the evolution of leaching gases would be closelymonitored to deter mine the rate at which new slurry is added to thesystem and the rate at which solution is withdrawn.

The amount of leaching gas required. to complete the dissolution of the,elements in the manganese phase can be determined byca'lculatiombut, inpractice, a small excess of gas, isalways required to assure completedissolution of the manganese, nickel, copper, etc., and thecontrolspreviously described, are of practical value in determining when theseelements have been completely dissolved;

'The rate. at which the manganese, nickel, and associated elements aredissolved will depend somewhat on the tempe'rature, pressure, andagitation of the slurry, but such variables are not critical noressential features of the process constituting the present invention.

There need be no external control of the pH of the from the cobalt.

to rise rapidly, as illustratedinthe drawing.

' The iron-cobalt tails are then removed from the vessel, dewatered,filtered, and washed,and then treated in a standard manner withacid toleach the cobalt from the iron. The leaching of the cobalt from the ironwith acid is a standard process in the metallurgical industry;

The solution of manganese, nickel, copper, etc., can be treated withhydrogen sulphide to precipitate the copper, which is then separatedfrom the remaining manganesenickel solution by standard dewatering andfiltering'techniques. Nickel can then be'separated from the manganese byprecipitation with hydrogen gas, or the manganese can be firstseparatedfrom the nickel by differential thermal reduction. The separation of thenickel. from the manganese or the manganese from the nickel wouldbe'conducted according to standard procedures. 1

The make up of the manganiferous ores found strewn over the ocean floor,lends itself to other methods of differentially leaching to eifectseparation of the nickel One such additional'method which comes to mind,involvessubjecting the ore material to preleaching reduction roasts, Thecommon factor in carrying out the present process, however, is to effecta While I have described my invention in its preferredform and inconsiderable detail, it will be apparentthat the same is subject toalteration and modification without departing from the underlyingprinciples involved, sear,

1. The method of separating the nickel from cobalt in ocean floormanganiferous deposits, in which the nickel is present in a manganeseoxide phase and the cobalt in an iron oxide phase, comprising, breakingup such ore, V I, leaching under reducing conditions in a solution themanganese phase and'included nickel fronljthe iron phase including thecobalt, then removing such manganese phase in solution before anyappreciable amount of the elements in the iron phase are dissolved, andprocessing the same to remove the nickel,

V to remove the cobalt. 2. The method of separating the nickel fromcobalt in H ocean floor manganiferous deposits, in which the nickel ispresent in a manganese oxide phase and the cobaltin an iron oxide phase,comprising,

breaking up. such ore, mixing'said ore in its broken up state withwater' to form a slurry,

mixing with said slurry a leachingagent capable of reducing manganeseand iron oxides, continuing the addition. of such leaching agent andhalting the same before any appreciable amount of the elements in theiron'phase are dissolved, and

then removing the solutionot manganese, and nickel is present in amanganese oxide phase and the'cobalt in,

an iron oxide phase, comprising,

crushing such ore to about minus forty mesh,

and separately processing the iron phase remaining,

mixing said ore in its crushed state with water to form an aqueousslurry,

mixing with said slurry a reducing and leaching agent capable in thepresence of water of reducing manan aqueous slurry,

mixing with said slurry a reducing and leaching gas capable in thepresence of water of reducing manganese and iron oxides,

continuing the addition of such leaching gas and haltganese and ironoxides, 5 ing the same before any appreciable amount of the continuingthe addition of such leaching agent and haltelements in the iron phaseare dissolved, and

mg the Same before y appreclable amount of the then removing thesolution of manganese and nickel elements in the iron phase aredissolved, and f h resulting cobaltqmn i1 then removing the solution ofmanganese and nickel from the r s l ing co alt-iron i 10 ReferencesCited in the file of this patent 4. The method of separating the nickelfrom cobalt in UNITED STATES PATENTS ocean floor mangamferous deposits,in which the mckel is present in a manganese oxide phase and the cobaltin 2,197,185 Klssock P 1940 an iron oxide phase, comprising 2,816,015Donaldson 1957 crushing such ore to about minus forty mesh, 15 2345333Schaufelberger July 291 1958 mixing said ore in its crushed state withwater to form 2,913,334 Dean 1959

1. THE METHOD OF SEPARATING THE NICKEL FROM COBALT IN OCEAN FLOORMANGANIFEROUS DEPOSITS, IN WHICH THE NICKEL IS PRESENT IN A MANGANESEOXIDE PHASE AND THE COBALT IN AN IRON OXIDE PHASE, COMPRISING, BREAKINGUP SUCH ORE, LEACHING UNDER REDUCING CONDITIONS IN A SOLUTION, THEMANGANESE PHASE AND INCLUDED NICKEL FROM THE IRON PHASE INCLUDING THECOBALT, THEN REMOVING SUCH MANGANESE PHASE IN SOLUTION BEFORE ANYAPPRECIABLE AMOUNT OF THE ELEMENTS IN THE IRON PHASE ARE DISSOLVED, ANDPROCESSING THE SAME TO REMOVE THE NICKEL, AND SEPARATELY PROCESSING THEIRON PHASE REMAINING, TO REMOVE THE COBALT.